This invention relates to the treatment of esophageal varices, and more particularly to a minimally invasive procedure using a catheter-based system to intravenously deploy an electrode for providing radio frequency (RF) energy, microwave energy, or thermal energy to shrink a dilated vein to change the fluid flow dynamics and to restore the proper function of the vein.
Blood returns to the heart from the portal venous system through the veins surrounding the esophagus. Unlike other veins, such as the saphenous vein in the lower leg, the veins surrounding the esophagus typically do not have valves for bringing blood back to the heart. The venous pressure in these esophageal veins is relatively high, and blood can flow back to the heart without aid of venous valves.
Varicose veins may result from vein dilation, in which the vein walls weaken, stretch, and swell with additional blood. Varicose veins called esophageal varices can form in the venous system along the submucosa of the lower esophagus, and bleeding can occur from the dilated veins. Esophageal varices may result from portal hypertension and other abnormalities in the portal venous system, such as cirrhosis of the liver. Bleeding or hemorrhaging may result from esophageal varices, which can be difficult to stop and, if untreated could develop into a life threatening condition. Such varices can erode easily, and lead to a massive gastrointestinal hemorrhage.
Treatments for esophageal varices include portal-caval shunts, endoscope variceal ligation, sclerotherapy, and electrocoagulation from an electrode within the esophagus, such as from a tamponade device. The portal shunt involves the surgical joining of two veins, the portal vein and the inferior vena cava, to relieve pressure in the vein carrying blood into the liver. Although effective in eliminating recurrent hemorrhaging from varices, the attendant risks and complications of such invasive surgery, including encephalopathy and post-shunt hepatic failure, still exist for the portal shunt operation.
Endoscopic variceal ligation is analogous to rubber band ligation for treating hemorrhoids. The esophageal varices are ensnared with elastic bands to eradicate the varices. An endoscope is introduced into the patient and is placed adjacent to the esophageal varices to be treated. The varix is drawn into a drum attached to the tip of the endoscope. An elastic band mounted on the drum is then released over the varix. Endoscope variceal ligation may not achieve complete fibrosis of the inner wall of the esophagus, and recurrence of the varices may result. Other complications include bleeding from ulcers induced by the elastic bands, and esophageal obstruction due to occlusion of the lumen by banded esophageal varices.
In sclerotherapy, a solution, such as sodium morrhuate or ethanolamine, is injected submucosally into the tissue around the varicose vein in the esophagus to cause inflammation and scarring to close off the vein and reduce the likelihood of bleeding. Sclerotherapy, however, may create ulcerations which can lead to esophageal strictures.
Electrocoagulation has also been used to treat esophageal varices. A tamponade device having a metalized surface is introduced into the esophagus. The metalized surface is brought into contact with the mucous membrane of the esophagus. An electric current is then applied to the metalized surface to cause a thrombosing of the esophageal varices. This procedure may be employed to stop immediate hemorrhaging of the esophageal varices.
The prior treatments for esophageal varices typically involve external coagulation or obliteration of the veins, and often require multiple treatment sessions. Such treatments do not treat the varicosity directly, and may not affect the underlying causes which gave rise to the esophageal varices initially.
A need exists in the art to treat the dilated veins which give rise to esophageal varices and reduce venous pressure on the esophageal region from the portal vein system without the attendant risks of invasive surgery. Further need exists to provide a less invasive procedure which can treat multiple venous sites quickly and easily. The need exists to restore and normalize flow patterns, dynamics, and pressure, and shrink sections of dilated veins to a normal or reduced diameter. Where bleeding occurs, there is a need to achieve hemostasis in bleeding varices and minimize recurrence of bleeding.